Many methods and apparatus are known in the art for the purpose of decomposing, in an economical and environmentally acceptable manner, waste products resulting from agricultural and forestry, vegetable production and horticulture, landscape and park maintenance, as well as excrement and the like, by anaerobic fermentation and/or aerobic decomposition and of simultaneously producing a good fertilizer, as well as heat for heating purposes or the like. However, so far as is known, such systems have not been designed, utilized and controlled to primarily develop heat energy for hygienically heating an air space of an enclosed structure, such as a greenhouse, in a passive manner through a self-powered heat transfer mechanism from a biomass material heat generating source.
The most common method of heating a greenhouse in a commercial setting is with the use of fossil fuels such as natural gas, fuel oil, etc. However, there is an on-going need for any alternative that will provide a more efficiently controlled interior environment suitable for plant production. It has long been known that burning biomass will generate energy that can reduce dependency on fossil fuel sources. However, environmental and economical restrictions have impeded these developments within the commercial industry. Burning biomass, in itself, can be viewed as an inefficient use of energy; the fuel is consumed quickly, causing a rapid energy release, much of which can be lost up the exhaust stacks.
The present invention, therefore, has responded to the challenge to research a renewable and environmentally sustainable alternative, and has done so by extracting the heat of decomposition from biomass over an extended period of time. This passive system of the invention thus provides a significant means of respite to the energy intensive greenhouse industry.
Under normal circumstances, the basic principles of composting are quite simple and adhering to them will result in an efficient and successful outcome. Composting has become an excellent way to manage certain wastes responsibly, prevent the wasting of natural resources, and produce a value-added, inexpensive soil amendment product. Composting also generates another valuable resource that may be recaptured and re-used, namely, heat energy.
However, harvesting this heat energy source for a commercial use such as greenhouse heating, presents new challenges. This form of heat energy is unlike any standard within the heat transfer industry. To heat a greenhouse structure from this heat energy source, it must be viewed in three separate components:                a) heat energy generation,        b) heat transfer, and        c) heat distribution/use.        
Heat distribution and use within a greenhouse facility is well documented with much information and data available. However, modifications should be pursued to enhance heat retention and use within these structures to maximize the heat re-capture benefits.
The most critical and difficult challenge in the development of the present invention comes in the heat energy generation phase. It has been proven that temperatures, in the best enhanced aerobic composting situations, can reach up to 180° F. by intensive aeration (oxygen replenishment) on a continual basis; this methodology is commonplace in the production of compost as a growing media used in mushroom operations. These high composting temperatures are a requirement for the safe destruction of any contained pathogens within the organic composting components used in mushroom growing operations. However, this particular method of composting may not be practical for the purpose pursued in the system of the invention because of the constant need to, in mushroom operations, mechanically aerate by turning and fluffing the piles or windrows. This form of composting is very rapid, causing the components to be “consumed” very quickly.
The underlying challenge in each case is to establish composting systems that will function within the designed confinement criteria. For greenhouse heating the need is for presenting a consistent temperature range of 140–160° F., sustainable for a practical time frame of up to 20 weeks, while mitigating the negative effects of the generated by-products. Compost component selection, means of aeration, moisture content maintenance, and by-product management are all of great importance to the development of a satisfactory biomass heat generation system that can present a suitable and affordable alternative to traditional heat energy sources, while demonstrating a positive effect on the environment. Further, to successfully accomplish this goal, engineering designs of the heat transfer and distribution systems need to be successfully customized to the needs of the particular and varying structural applications and parameters.